Study on Vibration Energy Conversion Efficiency of the Drill String Absorption & Hydraulic Supercharging Device

The vibration of a drill string can cause multiple hazards in the process of drilling operations. The conversion of excessive vibration energy of the drill string into the rock breaking energy can provide the dual effect of reducing the risks and improving the rock breaking efficiency of drilling. To address the task, a drill string absorption & hydraulic supercharging device has been developed. However, the design and exploitation of the drill string absorption & hydraulic supercharging device needs a comprehensive understanding of the characteristics of conversion of the drill string’s vibration energy. Based on the drill string dynamics experimental device, a simulation test platform has been developed to evaluate the efficiency of conversion of the vibration energy. The analysis of the test results is used to evaluate the conversion characteristics of the vibration energy of the bottom hole drill string. The results show that the energy conversion efficiency depends on the elastic stiffness and installation position of the drill string absorption & hydraulic supercharging device, the overall rotational speed, and the WOB (weight on bit) of the conversion device. With increase in the elastic stiffness, the conversion efficiency of the vibration energy first increases and then decreases. The closer the installation position of the drill string absorption & hydraulic supercharging device is to the bit, the better the conversion efficiency. With increase in the rotational speed, the conversion efficiency of the vibration energy increases. With increase in the WOB, the conversion efficiency of the vibration energy first increases and then decreases. The research results provide the background for the development and application of speed raising tools based on conversion of the drill string vibration.